1. Field of the Invention
The present invention relates to a stepless speed variator, especially to a stepless speed variator incorporated with a gear engaging orientational ON-OFF device.
2. Description of the Background Art
Along with the increasing development of engineering technique, the application of speed variatiors becomes more and more extensive. There have been a plurality of stepless speed variators used as mechanical, electrical (thyristor speed adjustment), and hydraulic (hydraulic motor speed adjustment), etc. The electrical and the hydraulic speed variators have rather narrow range of speed variation, high loss of efficiency and during variation they can not arrive at the result of inversely proportional torque output from any switching of torque and rotary speed. Among the mechanical speed variators there have been frictional wheel type, belt chain type and sleeve pawl type, etc., which primarily apply frictional force to transmit motion and power. Due to lower efficiency and limited power transmission of the frictional transmission there exists currently no technique in stepless speed variations with high efficiency and large power transmission by means of friction-drive. It is well known in practice that gear engaging variators allow high efficiency for large power transmission. However, up to the present it has not been possible to produce stepless speed variators in the way of gear engaging transmission without utilization of friction drive. This has become a difficult subject in the world.
And, up to now the self-locking feature of worm and worm wheel engagement transmission has still not yet obtained proper exploitation in the machinery industries, formerly only the ever going feature of clockwise and counterclockwise inputs of worm is known. However, the valuable feature and applied technique of its orientational ON-OFF performance is still not yet attached great importance by people.